Many of today's electronic devices are powered by direct current (DC) derived from an alternating current (AC) main power source. An AC to DC converter converts the AC power to a first DC voltage or current for powering the device. Many of these devices, for example, personal computers and televisions, are configured for coupling auxiliary devices thereto. In some cases an auxiliary electronics device operates using a second DC voltage or current different than the first DC voltage or current. In that case DC-DC converters are employed to convert the first DC voltage or current (i.e., the offline DC voltage) to the second DC voltage or current for powering the auxiliary device.
Regulation and isolation of the second DC voltage or current is desirable and is provided by conventional DC-DC converter circuits. However these DC-DC converter features have conventionally been implemented with custom-designed power controller circuits and components. In particular, conventional power controller circuits rely on optical couplers or isolating signal transformers to isolate the primary and secondary windings of an isolation transformer. Both solutions comprise discrete circuit components and are not suitable for implementing on monolithic integrated circuits. As a result conventional circuits typically comprise a plurality of discrete components, a plurality of integrated circuits and in some cases hybrid ICs to provide converter functions. While these circuits perform their functions well, they consume more space than is typically desirable. In addition they can be complex and expensive. It would therefore be desirable to provide an isolated off line power controller that could be integrated onto a single monolithic integrated circuit.